A 71-year-old male complained of a sudden attack of colour blindness and prosopagnosia. The colour blindness was red-green defect. Left homonymous hemianopsia was confirmed by red-target perimetry. Brain scanning suggested the lesion was to be in the right inferior occipital region. The symptoms disappeared spontaneously in three weeks. A 35-yearold male presented prosopagnosia and achromatopsia. These cases suggested that acquired colour blindness of central origin may exist and that the non-dominant hemisphere may play a specific role in the process of colour discrimination.